Such cutting inserts have lateral faces which intersect at a radiused corner having a given radius and forming a corner angle therebetween. The larger the corner angle the smaller the radius may be without concern of the corner breaking. If the corner of such a cutting insert is truncated, the angle formed between each lateral face and a face of the truncated corner is enlarged and as a result a radius connecting each lateral face and the face of the truncated corner may be smaller. A cutting edge associated with each lateral face and ending at a small radius forms more uniform chips which reduces wear to the cutting insert.
In order to increase the degree of indexability of the cutting insert, each lateral face should preferably form an identical angle with the face of the truncated corner. However, when the cutting insert has a standard entering angle of 45° between its cutting edge and the direction of feed, the face of the truncated corner may undesirably engage a workpiece.